Electrodeposition of nickel



United States Patent 3,334,032 ELECTRODEPOSITION OF NICKEL Otto Kardos, Rumson, NJJ., assignor to Hanson- Van Winkle-Munning Company, a corporation of New Jersey No Drawing. Filed May 8, 1964, Ser. No. 366,171 26 Claims. (Cl. 20449) This invention relates to electrodeposition and, more particularly, to the electroplating of nickel from an aqueous acidic nickel plating bath. The invention is based on the discovery that water soluble aliphatic bromine compounds containing the unsaturated bivalent radical --BrC=CBr or its corresponding saturated bivalent radical -Br C-CBI when incorporated in a plating bath are remarkably efiective as brighteners and possess strong leveling ability for promoting the formation of ductible electroplates which are much smoother than that of the basis metal.

We have found in all instances that using one of these water soluble aliphatic bromine compounds, particularly the ones that contain the unsaturated bivalent radical in combination with a sulfo-oxygen compound greatly improves the leveling capacity of the plating bath as compared with the use of its corresponding bromine free olefinic compound. The nickel deposits from this bath are brilliant, low stressed and much smoother than the basis metal. When any of these compounds is used alone as an addition agent without the sulfo-oxygen compound semibright, ductile, low stressed, and sulfur free nickel deposits of good corrosion resistance are obtained.

The water soluble aliphatic bromine compounds that have been found to be particularly elfective are the alcohols, polyalcohols, ether alcohols, and polyether alcohols which contain an unsaturated bivalent radical BrC=CBr or a saturated bivalent radical Br C'CBT Only relatively small quantities of these aliphatic bromine compounds are required in the plating bath. In general, concentrations as low as 0.1 millimole per liter have been found to produce a beneficial elfect. For some cases, however, as much as millimoles per liter are required to obtain the desired effect. Accordingly, a preferred process of this invention for producing semibright to bright nickel deposits comprises electrodepositing nickel from an aqueous acid solution of at least one nickel salt, in

which there is dissolved from about 0.1 to about 10 millimoles per liter of a water soluble aliphatic bromine compound which contains a bivalent radical selected from the group consisting of While any water soluble aliphatic bromine compound containing dibromo or tetrabromo bivalent radical can be 3,334,032 Patented Aug. 1, 1967 HOCH Br=CBrCH OH HOCH CH OCH CBr=CBrCH OCH CH OH HOCH CB1 CBrCH O(CH CH O) H O(CH CHgOCH C'BT CBI'CH OCH CH OH) (-CH OCH CB:CBrCH OCH CH OH) and the corresponding tetrabromo compounds obtained with 4 gram atoms of bromine per mole of butynediol. Compounds from among this group which have been found to be very satisfactory are those which have the formula selected from the group consisting of wherein each of R and R is a substituent selected from the group consisting of hydrogen and methyl radicals, each of R and R is a substituent selected from the group consisting of hydrogen, methyl and chloromethyl radicals, each of n and m is zero or an integer, and p is an integer. Concerning the usefulness of these compounds as nickel plating additives, no sharp upper limit was found for the ratio (n+m)/ p, but no specific advantage would be obtained by using this ratio greater than 2. Of these two classes of alcohols, polyalcohols, ether alcohols, and polyether alcohols represented by the formulas, the olefinic dibromo compounds generally have higher water solubility and great leveling capacity and are the preferred addition agents of this invention. Nevertheless, it is possible using the corresponding saturated tetrabromo compounds to obtain commercially acceptable semibright to bright nickel deposits.

Preparation of these compounds is well known in the art. A convenient method for making the dibromo olefine consists of controlled bromination of the corresponding acetylenic compounds. The resultant unsaturated dibromo olefines can be further treated with bromine to produce the saturated tetrabromo aliphatic compounds.

When the aliphatic bromine compounds of this invention are used in conjunction With a sulfo-oxygen compound, the amount of the latter compound that can be used in the nickel plating bath ranges from about 0.25

to about 80 grams per liter, preferably not more than 20 grams per liter. The sulfa-oxygen compounds used in the present invention are the water soluble type selected from the group consisting of unsaturated aliphatic sulfonic acids, mononuclear and polynuclear aromatic sulfonic acids, heterocyclic sulfonic acids, mononuclear aromatic sulfinic acids, alkali metal, ammonium, magnesium and nickel salts of said acid, and mononuclear aromatic sulfonamides and imides. Examples of sulfo-oxygen compounds are listed in Table I which when used with the aliphatic bromine compounds of this invention promote the formation of brilliant low stressed nickel deposits substantially smoother than the basis metal to which it is applied.

Table I.Sulf-oxygen compounds (1) Unsaturated aliphatic sulfonic acids, and alkali metal, ammonium, magnesium, and nickel salts thereof: Vinyl sulfonic acid, H C=CHSO H Sodium vinyl sulfonate, H C=CHSO Na Allyl sulfonic acid, H C=CHCH SO H Sodium allyl sulfonate, H C=CHCH SO Na Sodium propyne sulfonate, HCECCH SO Na Sodium propynoxy ethane sulfonate,

(2) Mononuclear aromatic sulfonic acids, and alkali metal, ammonium, magnesium and nickel salts thereof:

Benzene monosulfonic acid, C H SO H Sodium benzene monosulfonate, C H SO Na Nickel benzene monosulfonate, (C H SO H Ni Sodium para-toluene monosulfonate, CH C H SO Na Para-chlorobenzene sulfonic acid, ClC H SO H Sodium para-chlorobenzene sulfonate, ClC H SO Na Sodium para-bromobenzene sulfonate, BrC H SO Na 1,2 dichlorobenzene sulfonic acid, Cl C H SO H 1,2, or 2,5 dichlorobenzene sulfonate sodium salt,

Cl C5H3SO3Na;

Sodium phenylethylene sulfonate, C H CH=CHSO Na Para-vinyl benzene sulfonic acid, H C=CHC H SO H Ortho-formyl benzene sulfonic acid, O=CHC H SO H Meta benzene disulfonic acid, C H (SO H) 2 Sodium meta-benzene disulfonate, C H (SO Na) Nickel meta-benzene disulfonate, C H (SO Ni Ortho-sulfobenzoic acid monoammonium salt,

HOCOC H SO NH l-amino-2,5-benzene disulfonic acid, H NC H (SO H) Ortho-aminobenzene sulfonic acid, H NC H SO H (3) Mononuclear aromatic sulfinic acids, and alkali metal, ammonium, magnesium and nickel salts thereof:

Sodium benzene sulfinate, C H SO Na Sodium para-toluene sulfinate, CH C H SO Na (4) Mononuclear aromatic sulfonamides and imides:

Benzene sulfonamide, C H SO NH Para-toluene sulfonamide, CH C H SO NH Ortho-benzoic sulfimide,

C oHqC ONHS O1 Benzyl sulfonamide, C H CH SO NH Benzene sulfhydroxamic acid, C H SO NHOH Benzene sulfonyl cyanamide sodium salt,

C H SO N(Na)CN (5) Binuclear aromatic sulfonic acids and alkali metal, ammonium, magnesium, and nickel salts thereof:

Z-naphthalene monosulfonic acid, C10H'7SO3H 1,5 or 2,7-naphthalene disulfonic acid, C H (SO H) 1,5 or 2,7 -naphthalene disulfonic acid nickel salt,

Naphthalene t-risulfonic acid, C H (SO H) Naphthalene trisulfonic acid trisodium salt,

. 1o 5( s )3 Diphenyl pp disulfonic acid, HSO C H C H SO H 4 2-naphthol-3,6-disulfonic acid, HOC H (SO H) 2 2-naphthol-3,6-disulfonic acid sodium salt,

HOC H (SO Na) l-naphthylamine 3,6,8,trisulfonic acid,

z 1o 4( 3 )s (6) Heterocyclic sulfonic acids and alkali metal, ammonium, magnesium and nickel salts thereof:

Thiophene sulfonic acid, C H S-SO H Sodium thiophene sulfonate, C H S-SO Na Among these compounds, I found that allyl sulfonic acid, para-vinyl benzene sulfonic acid, -o-f0rmyl benzene sulfonic acid, vinyl sulfonic acid and their alkali metal or nickel salts are especially suitable to enhance the leveling capacity of the aliphatic bromine compounds of the present invention.

The addition agents of this invention have been used successfully in the standard Watts nickel electroplating bath. These brightener additions are also effective in all other acid nickel electroplating baths containing one 01' more nickel salts. Further to illustrate the invention, specific examples are described hereinbelow. Unless otherwise stated, a standard Watts nickel plating bath of the following composition was used in the examples:

G./liter NiSO -6H O 300 Niclz' H BO 42.0

Plating operations in each example were carried out in a 250 ml. Hull cell with vigorous air agitation at a total current of 2 amperes and a temperature of 60 C. for 10 or 15 minutes plating time as specified in the examples.

EXAMPLE I 0.001 mole per liter of 2,3 dibromo 2 butene 1,4- diol was added to the Watts plating bath containing 9.0 grams per liter of the sodium salt of hydroxy acetic acid (glycolic acid), for ten minutes. Improved semibright nickel deposits were obtained. The deposits were ductile, low stressed and sulfur free with good resistance to corrosion.

Similar experiments were conducted using 0.0004 to 0.0008 moles/liter of the dihydroxyethyl ether of 2, dibromo 2 butene 1,4 diol. The semibright appearance of nickel deposits was improved and the resultant nickel plates were ductile, low stressed and sulfur free with good resistance to corrosion.

EXAMPLE II The leveling effect exerted by the nickel plating baths containing various addition agents of the present invention and different sulfo-oxygen compounds were tested. This effect was measured in terms of decrease in roughness of the nickel electrodeposit compared to that of the underlying metal surface. It was determined by measuring the surface roughness of a brass panel with a Profilometer prior to the plating operation and then immediately following the plating operation. The brass panels used measured 2 /2 inches wide by 3% inches long which were roughened oveeahorizontal band by several strokes of emery paper to approximately the same initial roughness of 25 microinches RMS. After plating, the final surface roughness was measured at a spot corresponding to a current density of 70 amperes per square foot. For 10 minutes plating time, the thickness of the nickel deposits at this spot is about 0.6 ml.

The leveling effect exerted by similar nickel plating baths containing the corresponding bromine free olefinic compounds were also tested. The results of these wto sets of tests are listed in Table II. In all these tests, the resulting nickel deposits were low stressed and fully bright over almost the entire current density range of the Hull cell.

Final Aliphatic Bromine Plating Surface Tests Compound Sulfo-xygen Compound Time Roughness (min.) (Microinch RM S) A 2, 3-dibromo-2-buteneg./l. benzene sulfonic acid, 10. 5

1,4-diol (0.002 mole/1.). Na salt plus 0.4 g./1. saccharin. 2-butel1e-1,4-diol (0.002 10 24. 4

mole/1.).

B 2,3-dibromo-2-butene- 5 g./l. Na salt oi benzene 10 8. 4

1,4-diol (0.0012 mole/ sulfonic acid plus 0.4 g./l. 1.). saccharin plus 2 g./l. so-

dium allyl sulfonate. 2-butene-l,4-diol (0.0012 10 28. 7

mole/1.).

C 2,3-dibr0mo-2-pr0pene- 5 g./l. benzene sulfonic acid, 10 6. 5

1-01 (0.0016 mole/1.). Na salt plus 2 g./l. sodium allyl sullonate. 2-p1opene-1'0l (0.0016 10 37 mole/1.).

2,3-dibromo-1-hydroxy- 5 g./l. benzene sulfonic acid 10 12. 8

ethozy-Q-propene 1) us 2 g./l. sodium allyl D (0.001 mole/1.). sulfonate.

2-propenyl-oxyethanol 10 27. 5

(0.001 mole/1.).

EXAMPLE III and the sulfamate bath having the composition:

one having the additive of this invention. In the first set' of tests, two plating baths, both containing 5 g./l. of benzene sulfonic acid sodium salt and 2 g./l. 0f orthoformyl benzene sulfonic acid sodium salt were used with the second bath containing in addition 0.0005 mole/'1. of 2 butene 1,4 diol which has been reacted with 2 equivalents of ethylene oxide and twith two equivalents of bromine. Two brass plates were used for electrodeposition and the resultant nickel deposits after minutes plating time and 70 amp./ sq. ft. average current density were compared. It was found that nickel deposits from the bath without the additive compound of this invention showed little or no leveling effect while the bath containing the olefiuic bromine compound showed a reduction of surface roughness of 40%.

In the second set of tests, 5 g./l. of benzene sulfonic acid sodium salt and 1.2 g./l. of solium salt of paravinyl benzene sulfonic acid were added to the Watts bath. Addition of 0.001 mole per liter of the above butynediolethylene oxide-bromine reaction product increased the leveling of the fully bright nickel deposits from the original 22% to at a plating time of 15 minutes and an average current density of 70 amp/sq. ft. A third set of tests using a Watts bath containing 5 g./l. of benzene sulfonic acid sodium salt and 2 g./l. of allyl sulfonate produced fully bright nickel deposits. The addition of 0.001 mole/liter of the dibrominated reaction product of 1 mole of 2-butyne-1,4-diol with 1 mole of ethylene oxide reduced the surface roughness by 51%. Omitting these additives, the bath had negligible leveling capacity.

EXAMPLE IV The brightening and leveling capacity of the aliphatic bromine compounds in fluoborate nickel bath and sulfamate nickel bath are equally remarkable. In this exam ple, the fluoborate bath having the following composition:

. G./liter Total nickel (as metal) 75 NiCl2'6H2O H BO 57 G./liter Total nickel (as metal) 94 H BO 41 were used at 60 C. and at a pH of 3.4 to 3.6. The addition of 0.001 mole/l. of the dibrominated reaction products of 1 mole of 2-butyne-1,4-diol with 2 moles of ethylene oxide in either of these baths in the presence of 5 g./l. of benzene sulfonic acid sodium salt and 2 g./l. sodium allyl sulfonate or in its place 1 g./l. of the para-vinyl benzene sulfonic acid sodium salt produced fully bright nickel deposits with leveling percentages of 64 and 56% in the fluoborate bath and of 54 and 53% in the sul'famate bath, respectively. The plating time in all instances was 15 minutes and the average current density 70 amp/sq. ft.

EXAMPLE V To illustrate the brightening and leveling effects of a saturated aliphatic bromine compound 0.005 mole/liter of '2,2,3,3-tetra-bromo-2-'butane-1,4-diol was added to a Watts nickel bath containing 5 g./l. of the sodium salt of benzene sulfonic acid and 2 g./l. of sodium allyl sulfonate; after 15 minutes plating time at 70 amp/sq. it. average current density a fully bright nickel deposit showing a leveling of 42% was obtained. Other saturated aliphatic bromine compounds containing the bivalent radical Br CCBr have similar beneficial eitects in aqueous acid baths. Generally, the commercial application of this type of compound is limited only by its water solubility.

I claim:

1. A process for producing semibright to bright nickel deposits which comprises electrodepositing nickel from an aqueous acid solution of at least one nickel salt in which there is dissolved from about 0.1 to about 10 millimoles per liter of a water soluble aliphatic bromine compound which contains a bivalent radical selected from the group consisting of 2. A process for producing semibright to bright nickel deposits which comprises electrodepositing nickel from an aqueous acid solution of at least one nickel salt in which there is dissolved from about 0.1 to about 10 millimoles per liter of a water soluble aliphatic bromine compound selected from the group consisting of alcohols, polyalcohols, ether alcohols, and polyether alcohols, each of which contains a bivalent radical selected from the group con sisting of 4. A process for producing semibright to bright nickel deposits which comprises electrodepositing nickel from an aqueous acidic solution of at least one nickel salt in which there is dissolved from about 0.1 to about millimoles per liter of a Water soluble aliphatic bromine compound selected from the group conseisting of wherein each of R and R is a substituent selected from the group consisting of hydrogen and methyl radicals, each of R and R is a substituent selected from the group consisting of hydrogen, methyl and chloromethyl radicals, each of n and m is zero or an integer, and p is an integer.

5. A process for producing semibright to bright nickel deposits which comprises electrodepositing nickel from an aqueous acidic solution of at least one nickel salt in which there is dissolved from about 0.1 to about 10 millimoles per liter of a water soluble aliphatic bromine compound having the formula wherein each of R and R is a substituent selected from the group consisting of hydrogen and methyl radicals, each of R and R is a substituent selected from the group consisting of hydrogen, methyl and chloromethyl radicals, each of n and m is zero or an integer, and p is an integer.

6. A process for producing semibright ductile lowstressed, sulfur free and corrosion resistant nickel deposits which comprises electrodepositing nickel from an aqueous acid solution of at least one nickel salt in which there is dissolved from about 0.1 to about 10 millimoles per liter of a water soluble aliphatic bromine compound selected from the group consisting of 2,3-dibromo-2-butene-1,4-diol, 2,3-dibromo-2-propene-1-01, 2,3-dibromo-lhydroxyethoxy-Z-propene, the monohydroxyethylether of 2,3-dibromo-2-butene-1,4-diol, the reaction products of 1 mole of 2-butyne-1,4-diol with 2 moles of ethylene oxide and two gram atoms of bromine, and 3,4-dibromo-2- methyl-3-butene-2-ol.

7. A process for producing semibright, ductile, lowstressed, sulfur free and corrosion resistant nickel deposits which comprises electrodepositing nickel from an aqueous acid solution of at least one nickel salt in Which there is dissolved from about 0.1 to about 10 millimoles per liter of 2,3-dibromo-2-butene-l,4-diol.

8. A process for producing semibright, ductile, lowstressed, sulfur free and corrosion resistant nickel deposits which comprises electrodepositing nickel from an aqueous acid solution of at least one nickel salt in which there is dissolved from about 0.1 to about 10 millimoles per liter of the reaction product of 1 mole of 2-butyne-l,4 liol with 2 moles of ethylene oxide and 2 gram atoms of bromine.

9. A process for producing bright low-stressed nickel deposits substantially smoother than the basis metal to which it is applied which comprises electrodepositing nickel from an aqueous acid solution of at least one nickel salt in which there is dissolved (a) from about 0.1 to about 10 millimoles per liter of a water soluble aliphatic bromine compound which contains a bivalent radical selected from the group consisting of and (b) from about 0.25 to about 80 grams per liter of a water soluble sulfo-oxygen compound of the group consisting of unsaturated aliphatic sulfonic acids, mononuclear and polynuclear aromatic sulfonic acids, heterocyclic sulfonic acids, mononuclear aromatic sulfinic acids, alkali metal, ammonium, magnesium and nickel salts of said acids, and mononuclear aromatic sulfonamides and imides.

10. A process for producing bright low-stressed nickel deposits substantially smoother than the basis metal to which it is applied which comprises electrodepositing nickel from an aqueous acid solution of at least one nickel salt in which there is dissolved (a) from about 0.1 to about 10 millimoles per liter of a water soluble aliphatic bromine compound selected from the group consisting of alcohols, polyalcohols, ether alcohols, and polyether alcohols, each of which contains a bivalent radical and (b) from about 0.25 to about 80 grams per liter of a water soluble sulfo-oxygen compound of the group consisting of unsaturated aliphatic sulfonic acids, mononuclear and polynuclear aromatic sulfonic acids, heterocyclic sulfonic acids, monouclear aromatic sulfinic acids, alkali metal, ammonium, magnesium and nickel salts of said acids, and mononuclear aromatic sulfonamides and imides.

11. A process for producing bright low-stressed nickel deposits substantially smoother than the basis metal to which it is applied with comprises electrodepositing nickel from an aqueous acid solution of at least one nickel salt in which there is dissolved (a) from about 0.1 to about 10 millimoles per liter of a water soluble aliphatic bromine compound selected from the group consisting of 2,3-dibromo-2-butene-1,4-diol, 2,3-dibromo-2-propene-lol, 2,3-dibromo-1-hydroxyethoxy-2-propene, the monohydroxyethylether of 2,3-dibromo-2-butene-1,4-diol, reaction products of 1 mole of 2-butyne-l,4-diol, with 2 moles of ethylene oxide and 2 gram atoms of bromine, and 3,4-dibromo-2-methyl-3-butene-2-ol, and (b) from about 0.25 to about 20 grams per liter of a water soluble sulfo-oxygen compound of the group consisting of allyl sulfonic acid, para-vinyl benzene sulfonic acid, o-formyl benzene sulfonic acid, and vinyl sulfonic acid or their alkali metal or nickel salts.

12. A process for producing bright, low-stressed nickel deposits substantially smoother than the basis metal to which it is applied which comprises electrodepositing nickel from an aqueous acidic solution of at least one nickel salt in which there is dissolved (a) from about 0.1 to about 10 millimoles per liter of 2,3-dibromo-2-butene- 1,4-diol and (b) from about 0.25 to about 20 grams per liter of allyl sulfonic acid.

13. A process for producing bright, low-stressed nickel deposits substantially smoother than the basis metal to which it is applied which comprises electrodepositing nickel from an aqueous acid solution of at least one nickel salt in which there is dissolved (a) from about 0.1 to

about millimoles per liter of the reaction products of 1 mole of 2-butyne-1,4-diol with 2 moles of ethylene oxide and 2 gram atoms of bromine, and (-b) from about 0.25 to about 20 grams per liter of allyl sulfonic acid.

14. A nickel electroplating bath for producing semibright to bright nickel deposits which comprises an aqueous acid solution of at least one nickel salt in which there is dissolved from about 0.1 to about 10 millimoles per liter of a water soluble aliphatic bromine compound which contains a bivalent radical selected from the group consisting of 15. A nickel electroplating bath for producing semibright to bright nickel deposits which comprises an aqueous acid solution of at least one nickel salt in which there is dissolved from about 0.1 to about 10 millimoles per liter of a water soluble aliphatic bromine compound selected from the group consisting of alcohols, polyalcohols, ether alcohols, and polyether alcohols, each of which contains a bivalent radical selected from the group consisting of 16. A nickel electroplating bath for producing semibright to bright nickel deposits which comprises an aqueous acid solution of at least one nickel salt in which there is dissolved from about 0.1 to about 10 millimoles per liter of a water soluble aliphatic bromine compound selected from the group consisting of alcohols, polyalcohols, ether alcohols, and polyether alcohols, each of which contains the bivalent radical 17. A nickel electroplating bath for producing semibright to bright nickel deposits which comprises an aqueous acidic solution of at least one nickel salt in which there is dissolved from about 0.1 to about 10 millimoles per liter of a water soluble aliphatic bromine compound selected from the group consisting of wherein each of R and R is a substituent selected from the group consisting of hydrogen and methyl radicals, each of R and R is a substituent selected from the group consisting of hydrogen, methyl and chloromethyl radicals, each of n and m is zero or an integer, and p is an integer. 18. A nickel electroplating bath for producing semibright to bright nickel deposits which comprises an aqueous acidic solution of at least one nickel salt in which there is dissolved from about 0.1 to about 10 millimoles per liter of a water soluble aliphatic bromine compound having the formula wherein each of R and R is a substituent selected from the group consisting of hydrogen and methyl radicals, each of R and R is a substituent selected from the group consisting of hydrogen, methyl and chloromethyl radicals, each of n and m is Zero or an integer, and p is an integer.

19. A nickel electroplating bath for producing semibright, ductile, low-stressed, sulfur free and corrosion resistant nickel deposits which comprises an aqueous acid solution of at least one nickel salt in which there is dissolved from about 0.1 to about 10 millimoles per liter of a water soluble aliphatic bromine compound selected from the group consisting of 2,3-dibromo-2-butene-1,4-diol, 2, 3-dibromo-2-propene-l-ol, 2,3-dibromo-l-hydroxyethoxy- 2-propene, the monohydroxyethylether of 2,3-dibromo-2- butene-1,4-diol, reaction products of 1 mole of Z-butyne- 1,4-diol with 2 moles of ethylene oxide and 2 gram atoms of bromine and 3,4-dibromo-2-methyl-3-butene-2-o1.

20. A nickel electroplating bath for producing semibright, ductile, low-stressed, sulfur free and corrosion resistant nickel deposits which comprises an aqueous acid solution of at least one nickel salt in which there is dissolved from about 0.1 to about 10 millimoles per liter of 2,3-dibromo-2-butene-1,4-diol.

21. A nickel electroplating bath for producing semibright, ductile, low-stressed, sulfur free and corrosion resistant nickel deposits which comprises an aqueous acid solution of at least one nickel salt in which there is dissolved from about 0.1 to about 10 millimole per liter of the reaction products of 1 mole of 2-butyne-1,4-diol with 2 moles of ethylene oxide and 2 gram atoms of bromine, and 3,4-dibromo-2-methyl-3-butene-2-ol.

22. A nickel electroplating bath for producing bright low-stressed nickel deposits substantially smoother than the basis metal to which it is applied which comprises an aqueous acid solution of at least one nickel salt in which there is dissolved (a) from about 0.1 to about 10 millimoles per liter of a water soluble aliphatic bromine compound which contains a bivalent radical selected from the group consisting of and (b) from about 0.25 to about grams per liter of a water soluble sulfo-oxygen compound of the group consisting of unsaturated aliphatic sulfonic acids, mononuclear and polynuclear aromatic sulfonic acids, heterocyclic sulfonic acids, mononuclear aromatic sulfinic acids, alkali metal, ammonium, magnesium and nickel salts of said acids, and mononuclear aromatic sulfonamides and imides.

23. A nickel electroplating bath for producing bright low-stressed nickel deposits substantially smoother than the basis metal to which it is applied which comprises an aqueous acid solution of at least one nickel salt in which there is dissolved (a) from about 0.1 to about 10 millimoles per liter of a water soluble aliphatic bromine compound selected from the group consisting of alcohols, polyalcohols, ether alcohols, and polyether alcohols, each of which contains a bivalent radical and (b) from about 0.25 to about 20 grams per liter of a water soluble sulfo-oxygen compound of the group consisting of unsaturated aliphatic sulfonic acids, mononuclear and polynuclear aromatic sulfonic acids, heterocyclic sulfonic acids, mononuclear aromatic sulfinic acids, alkali metal, ammonium, magnesium and nickel salts of said acids, and mononuclear aromatic sulfonamides and imides.

24. A nickel electroplating solution for producing bright low-stressed nickel deposits substantially smoother than the basis metal to which it is applied which comprises an aqueous acid solution of at least one nickel salt in which there is dissolved (a) from about 0.1 to about 10 millimoles per liter of a water soluble aliphatic bromine compound selected from the group consisting of 2,3-dibromo- 2-butene-1,4-diol, 2,3-dibromo-2-propene-l-ol, 2,3 dibromo-1-hy'droxyethoxy-2 propene, the monohydroxyethylether of 2,3-dibromo-2-butene-1,4-diol, the reaction products of 1 mole of 2-butyne-1,4-diol with 2 moles of ethylene oxide and 2 gram atoms of bromine and 3,4-dibromo-2-methyl-3-butene-2-ol, and (b) from about 0.25 to about 20 grams per liter of a water soluble sulfo-oxygen compound of the group consisting of allyl sulfonic acid, para-vinyl benzene sulfonic acid, o-formyl benzene sulfonic acid, and vinyl sulfonic acid or their alkali metal or nickel salts.

25. A nickel electroplating bath for producing bright low-stressed nickel deposits substantially smoother than the basis metal to which it is applied which comprises an aqueous acidic solution of at least one nickel salt in which there is dissolved (a) from about 0.1 to about 10 millimoles per liter of 2,3-dibr0mo-2-butene-1,4-diol, and (b) from about 0.25 to about 20 grams per liter of allyl sulfonic acid.

26. A nickel electroplating bath for producing bright low-stressed nickel deposits substantially smother than the basis metal to which it is applied which comprises an aqueous acidic solution of at least one nickel salt in which 12 there is dissolved (a) from about 0.1 to about 10 millimoles per liter of the reaction products of 1 mole of 2- butyne-1,4-diol with 2 moles of ethylene oxide and 2 gram atoms of bromine and 3,4-dibromo-2-methyl 3- butene-2-ol, and b) from about 0.25 to about 20 grams per liter of allyl sulfonic acid.

References Cited UNITED STATES PATENTS 2,321,182 6/1943 Brown 204-49 3,002,904 10/1961 Foulke et a1 20449 3,218,244 11/1965 Passal et al 20449 JOHN H. MACK, Primary Examiner.

G. KAPLAN, Assistant Examiner. 

1. A PROCESS FOR PRODUCING SEMIBRIGHT TO BRIGHT NICKEL DEPOSITS WHICH COMPRISES ELECTRODEPOSITING NICKEL FROM AN AQUEOUS ACID SOLUTION OF AT LEAST ONE NICKEL SALT IN WHICH THERE IS DISSOLVED FROM ABOUT 0.1 TO ABOUT 10 MILLIMOLES PER LITER OF A WATER SOLUBLE ALIPHATIC BROMINE COMPOUND WHICH CONTAINS A BIVALENT RADICAL SELECTED FROM THE GROUP CONSISTING OF 